Motor-driven line transfer control

ABSTRACT

An oscillatory shaft line switch is driven by means of a motor which is responsive to load line voltage emergencies. A lever on the shaft of the line switch is connected by a link to a second lever on the shaft of a gear reduction box of the motor. The second lever is loose. Fixed to the shaft of the box is a crank having a bent outer end which turns the second lever as the motor turns. The first mentioned shaft has a contactor which engages either of two micro-switches to de-energize the motor after the line switch has been thrown in either direction. The loose connection of the second lever enables the first lever to be thrown by hand when necessary.

Loffler et a].

[451 Mar. 12, 1974 MOTOR-DRIVEN LINE TRANSFER CONTROL Inventors: ErichW. Loffler; Hans Kruger,

. both of 2466 Bay Rd., Redwood City, Calif. 90263 Filed: May 10, 1973Appl. No.: 359,018

Related US. Application Data Continuation-impart of Ser. No. 238,280,March 27, 1972, Pat. No. 3,736,054.

US. Cl. 318/468, 200/153 T, 335/69 Int. Cl. HOlh 3/02 .Field of Search318/468; 200/153 T;

Palmer et al 335/68 Engelhardt 335/69 Bottonari et a1 335/69 PrimaryExaminer-B. Dobeck Attorney, Agent, or Firm-Julian Caplan [5 7] ABSTRACTAn oscillatory shaft line switch is driven by means of a motor which isresponsive to load line voltage emergencies. A lever on the shaft of theline switch is connected by a link to a second lever on the shaft of agear reduction box of the motor. The second lever is loose. Fixed to theshaft of the box is a crank having a bent'outer end which turns thesecond lever as the motor turns. The first mentioned shaft has acontactor which engages either of two micro-switches to deenergize themotor after the line switch has been thrown in either direction. Theloose connection of the second lever enables the first lever to bethrown by hand when necessary.

3 Claims, 2 Drawing Figures Pmmmmz 1974 3796937 MOTOR-DRIVEN LINETRANSFER CONTROL This application is a continuation-in-part of ourcopending application Ser. No. 238,280, filed Mar. 27, 1972 now US. Pat.No. 3,736,054.

This invention relates to a motor-driven line transfer control. Thecontrol is used with a commercially available, mechanically held linetransfer control switch which is movable between two positions-onewherein the utility power lines are connected to the load, and the otherwherein emergency power generator facilities are connected to the loadin emergencies when the normal line supply is temporarily not available.The present invention provides means to actuate the switch between oneposition and the other. Equipment which is used in connection with thedevice, but which is not a part of the present invention, senses whenany phase of the utility line voltage drops below a preselected point,such as 70 percent of normal. When this occurs, the sensing means startsa generator for the auxiliary source; when this source has brought theemergency line voltage up to 90 percent of needed voltage, then thepresent invention provides a means to throw the line transfer controlswitch from normal line position to emergency line position. In theevent either that the emergency line voltage drops below a preselectedpoint, or in the event that the normal line voltage is re-.

stored so that it builds up to a preselected percentage such as 90percent of normal voltage, then the sensor also causes the control ofthe present invention to throw the line transfer control switch back tonormal position.

It is, accordingly, a principal purpose of the present invention toprovide a motor-driven means energized depending upon the sensing of thenormal line and emergency line voltages to throw the aforementionedswitch between one position and another.

One of the features of the invention is the fact that the line transfercontrol switch, which is commercially available, need not be altered inits interior in any manner, and hence there is no impairment of thefunction of such switch. The switch actuating lever, moreover, isexposed for manual actuation where, for one reason or another, anoperator wishes to move the switch between its two positions and thusoverride the control switch of the present invention. This feature isimportant in emergencies when the sensing devices have failed.

Other objects of the present invention will become apparent upon readingthe following specifications and referring to the accompanying drawingsin which similar characters of reference represent corresponding partsin each of the several views.

In the drawings:

FIG. 1 is a top plan view of the structure.

FIG. 2 is a side elevational view thereof.

The switch 11 is a commercially available switch, a suitable example ofwhich is a Blue Line produced by Kraus & Naimer Gmbl-l of Austria. Thedetails of such switch are not part of the present invention and are notherein illustrated. However, such switch 11 has a main shaft 12 whichoscillates through a travel of approximately 60 and by mechanical meanssuch as a cam held in each of its positions. The number of sets ofswitch contacts in switch 11 is subject to variation. For purpose of thepresent invention, it may be assumed to be a three-phase switch havingthree sets of contacts.

Each set consists of a main, or normal, line contact which is connectedto the public utility power line, an emergency contact which isconnected to an emergency generator, which may be diesel operated, and aload contact which is connected by buss bars to a load. Emergency poweris required in many installations such as hospitals where any failure ofthe utility line power or the falling of the voltage thereof beyond apreselected percentage of normal may be very dangerous. Standbyemergency equipment is available in such locations and means is providedto sense when the line voltage diminishes beyond percent of ratedvoltage in any phase, whereupon the emergency generator prime mover isstarted and the emergency line is brought up to a percentage of itsrated capacity, such as percent. At this point, it is desirable toswitch the load from the utility line to the emergency line. If for anyreason the emergency line fails, it may be desirable to switch back tothe utility line and the sensor senses when the emergency line voltagediminishes beyond a certain percentage of normal capacity. After thecause of the utility line voltage drop has been remedied, the main linevoltage rises; when it reaches a preselected percentage of normal orrated value, then it is desirable to discontinue the emergency supplyand to transfer to the public utility line. Oscillation of the shaft 12accomplishes the switching.

The outer end of shaft 12, which is preferably noncircular, is providedwith an exposed first lever 13 which may be manually used to move theshaft 12 through an approximately 60 travel. The present inventionprovides a motor-driven means for moving shaft 12, as hereinafterexplained.

One end of elongated link 14 is connected by pivot bolt 16 to a point onlever 13 approximately one-third of the distance from shaft 12, leavingthe remaining length of lever 13 to function as a handle for manualactuation. The opposite end of link 14 is connected by means of pivotbolt 18 to approximately the midpoint of loose (second) lever 17 withspacer bushing 19 interposed between link 14 and lever 17. Lever 17 isfreely rotatable about the output shaft 21 of gear box 22. Gear box 22is driven in one direction only by means of electric motor 23 which issupported by bracket 24 from the frame 25 attached to the body of switch11.

Fixed to shaft 21 between lever 17 and gear box 21 is fixed (third)lever 26 which has an outward bent end 27. As lever 26 rotates on shaft21, the end 27 engages lever 17 and causes it to turn and this inconsequence causes lever 13 to oscillate. However, because there is nopositive connection between levers 26 and 17, the handle portion oflever 13 may be grasped and the shaft 12 thrown independently of motor23.

Mounted on subframe 31 fastened to switch 11 are two micro-switches 32a,32b which function as limit switches and each of which has a switchcontact 33 and a spring 34. Fixed to shaft 12 is a switch contactor 36which projects to a position between the switches 32a, 32b. When lever13 has been thrown to the limit of one of its positions by means ofturning of motor 23, the contactor 36 engages one or the other of thetwo micro-switches and through a relay system the motor 23 isde-energized. The motor 23 is re-energized only by operation of thesensor of line voltages which has heretofore been mentioned. To simplifythe electrical wiring of the device, preferably one of the switches 32a,32b is normally open and the other normally closed.

In operation, when the sensor senses that the line voltage or any of thephases thereof has fallen below a preselected level, then through arelay system it energizes motor 23 which turns shaft 21 and causes thelever 26 to turn in a clockwise direction. As said lever 26 revolves,the end 27 thereof contacts lever 17 and begins to turn said lever. Thisin turn moves link 14, which causes the lever 13 to be shifted 60 in theopposite direction from that where it was originally. When this shiftingmovement has been completed, contactor 36 engages one of themicro-switches 32a, 32b and this causes de-energization of the motor 23.After the emergency has ceased to exist, the motor 23 is re-energizedand the lever 13 is oscillated to the opposite position and motor 23 isstopped by micro-switch 32a or 32b. If, at any time, the operator needsto throw switch 11, he may grip the outer or handle portion of lever 13and turn the shaft 12 the desired angular distance. This movement ispossible because lever 17 is loose on shaft 21 and the connection oflever 26 to lever 17 is not positive but enables the lever 17 to beturned in a clockwise direction in advance of turning of lever 26.

What is claimed is:

1. A control for a line transfer switch comprising an oscillatoryoperating shaft having a limited angular movement and switch meansturned by said operating shaft, a first lever fixed to and extending outfrom said operating shaft, a switch contactor fixed to said operatingshaft, a first and a second micro-switch, means mounting saidmicro-switches relative to said line transfer switch so that said firstmicro-switch is contacted by said contactor when said operating shaftreaches the limit of its oscillatory angular movement in one directionand said second micro-switch is contacted by said contactor when saidoperating shaft reaches the limit of its movement in the otherdirection, a motor arranged to rotate in a single direction, a gear boxdriven by said motor having an output shaft, a second lever fixed forrotation with said output shaft through 360, 21 third lever freelyrotatable about said output shaft, a link pivotally interconnecting saidthird and first levers, said second lever having means to turn saidthird lever only in one direction, said motor when energized turningsaid second lever in said one direction and said second lever therebyturning said third lever through a 360 travel, said link oscillatingsaid first lever, said microswitches being connected to de-energize saidmotor when either of said micro-switches is contacted by said contactor.

2. A control according to claim 1 in which said second lever has anupturned extremity positioned to engage behind said third lever to causerotation of said third lever as said second lever rotates, said thirdlever being freely rotatable in advance of said second lever.

3. A control according to claim 1 in which said link is connected tosaid first lever inward of its outer end to provide a handle formanually oscillating said first lever independently of said motor.

1. A control for a line transfer switch comprising an oscillatoryoperating shaft having a limited angular movement and switch meansturned by said operating shaft, a first lever fixed to and extending outfrom said operating shaft, a switch contactor fixed to said operatingshaft, a first and a second micro-switch, means mounting saidmicro-switches relative to said line transfer switch so that said firstmicro-switch is contacted by said contactor when said operating shaftreaches the limit of its oscillatory angular movement in one directionand said second micro-switch is contacted by said contactor when saidoperating shaft reaches the limit of its movement in the otherdirection, a motor arranged to rotate in a single direction, a gear boxdriven by said motor having an output shaft, a second lever fixed forrotation with said output shaft through 360*, a third lever freelyrotatable about said output shaft, a link pivotally interconnecting saidthird and first levers, said second lever having means to turn saidthird lever only in one direction, said motor when energized turningsaid second lever in said one direction and said second lever therebyturning said third lever through a 360* travel, said link oscillatingsaid first lever, said micro-switches being connected to de-energizesaid motor when either of said micro-switches is contacted by saidcontactor.
 2. A control according to claim 1 in which said second leverhas an upturned extremity positioned to engage behind said third leverto cause rotation of said third lever as said second lever rotates, saidthird lever being freely rotatable in advance of said second lever.
 3. Acontrol according to claim 1 in which said link is connected to saidfirst lever inward of its outer end to provide a handle for manuallyoscillating said first lever independently of said motor.